rvlc.c

这是著名的TCPMP播放器在WINDWOWS,和WINCE下编译通过的源程序.笔者对其中的LIBMAD库做了针对ARM MPU的优化. 并增加了词幕功能.

/*
** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
** Copyright (C) 2003-2004 M. Bakker, Ahead Software AG, http://www.nero.com
**  
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
** 
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
** 
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software 
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
**
** Any non-GPL usage of this software or parts of this software is strictly
** forbidden.
**
** Commercial non-GPL licensing of this software is possible.
** For more info contact Ahead Software through [e-mail].
**
** $Id: rvlc.c,v 1.17 2004/09/04 14:56:28 menno Exp $
**/

/* RVLC scalefactor decoding
 *
 * RVLC works like this:
 *  1. Only symmetric huffman codewords are used
 *  2. Total length of the scalefactor data is stored in the bitsream
 *  3. Scalefactors are DPCM coded
 *  4. Next to the starting value for DPCM the ending value is also stored
 *
 * With all this it is possible to read the scalefactor data from 2 sides.
 * If there is a bit error in the scalefactor data it is possible to start
 * decoding from the other end of the data, to find all but 1 scalefactor.
 */

#include "common.h"
#include "structs.h"

#include <stdlib.h>

#include "syntax.h"
#include "bits.h"
#include "rvlc.h"


#ifdef ERROR_RESILIENCE

//#define PRINT_RVLC

/* static function declarations */
static uint8_t rvlc_decode_sf_forward(ic_stream *ics,
                                      bitfile *ld_sf,
                                      bitfile *ld_esc,
                                      uint8_t *is_used);
#if 0
static uint8_t rvlc_decode_sf_reverse(ic_stream *ics,
                                      bitfile *ld_sf,
                                      bitfile *ld_esc,
                                      uint8_t is_used);
#endif
static int8_t rvlc_huffman_sf(bitfile *ld_sf, bitfile *ld_esc,
                              int8_t direction);
static int8_t rvlc_huffman_esc(bitfile *ld_esc, int8_t direction);


uint8_t rvlc_scale_factor_data(ic_stream *ics, bitfile *ld)
{
    uint8_t bits = 9;

    ics->sf_concealment = faad_get1bit(ld
        DEBUGVAR(1,149,"rvlc_scale_factor_data(): sf_concealment"));
    ics->rev_global_gain = (uint8_t)faad_getbits(ld, 8
        DEBUGVAR(1,150,"rvlc_scale_factor_data(): rev_global_gain"));

    if (ics->window_sequence == EIGHT_SHORT_SEQUENCE)
        bits = 11;

    /* the number of bits used for the huffman codewords */
    ics->length_of_rvlc_sf = (uint16_t)faad_getbits(ld, bits
        DEBUGVAR(1,151,"rvlc_scale_factor_data(): length_of_rvlc_sf"));

    if (ics->noise_used)
    {
        ics->dpcm_noise_nrg = (uint16_t)faad_getbits(ld, 9
            DEBUGVAR(1,152,"rvlc_scale_factor_data(): dpcm_noise_nrg"));

        ics->length_of_rvlc_sf -= 9;
    }

    ics->sf_escapes_present = faad_get1bit(ld
        DEBUGVAR(1,153,"rvlc_scale_factor_data(): sf_escapes_present"));

    if (ics->sf_escapes_present)
    {
        ics->length_of_rvlc_escapes = (uint8_t)faad_getbits(ld, 8
            DEBUGVAR(1,154,"rvlc_scale_factor_data(): length_of_rvlc_escapes"));
    }

    if (ics->noise_used)
    {
        ics->dpcm_noise_last_position = (uint16_t)faad_getbits(ld, 9
            DEBUGVAR(1,155,"rvlc_scale_factor_data(): dpcm_noise_last_position"));
    }

    return 0;
}

uint8_t rvlc_decode_scale_factors(ic_stream *ics, bitfile *ld)
{
    uint8_t result;
    uint8_t intensity_used = 0;
    uint8_t *rvlc_sf_buffer = NULL;
    uint8_t *rvlc_esc_buffer = NULL;
    bitfile ld_rvlc_sf, ld_rvlc_esc;
//    bitfile ld_rvlc_sf_rev, ld_rvlc_esc_rev;

    if (ics->length_of_rvlc_sf > 0)
    {
        /* We read length_of_rvlc_sf bits here to put it in a
           seperate bitfile.
        */
        rvlc_sf_buffer = faad_getbitbuffer(ld, ics->length_of_rvlc_sf
            DEBUGVAR(1,156,"rvlc_decode_scale_factors(): bitbuffer: length_of_rvlc_sf"));

        faad_initbits(&ld_rvlc_sf, (void*)rvlc_sf_buffer, bit2byte(ics->length_of_rvlc_sf));
//        faad_initbits_rev(&ld_rvlc_sf_rev, (void*)rvlc_sf_buffer,
//            ics->length_of_rvlc_sf);
    }

    if (ics->sf_escapes_present)
    {
        /* We read length_of_rvlc_escapes bits here to put it in a
           seperate bitfile.
        */
        rvlc_esc_buffer = faad_getbitbuffer(ld, ics->length_of_rvlc_escapes
            DEBUGVAR(1,157,"rvlc_decode_scale_factors(): bitbuffer: length_of_rvlc_escapes"));

        faad_initbits(&ld_rvlc_esc, (void*)rvlc_esc_buffer, bit2byte(ics->length_of_rvlc_escapes));
//        faad_initbits_rev(&ld_rvlc_esc_rev, (void*)rvlc_esc_buffer,
//            ics->length_of_rvlc_escapes);
    }

    /* decode the rvlc scale factors and escapes */
    result = rvlc_decode_sf_forward(ics, &ld_rvlc_sf,
        &ld_rvlc_esc, &intensity_used);
//    result = rvlc_decode_sf_reverse(ics, &ld_rvlc_sf_rev,
//        &ld_rvlc_esc_rev, intensity_used);


    if (rvlc_esc_buffer) faad_free(rvlc_esc_buffer);
    if (rvlc_sf_buffer) faad_free(rvlc_sf_buffer);

    if (ics->length_of_rvlc_sf > 0)
        faad_endbits(&ld_rvlc_sf);
    if (ics->sf_escapes_present)
        faad_endbits(&ld_rvlc_esc);

    return result;
}

static uint8_t rvlc_decode_sf_forward(ic_stream *ics, bitfile *ld_sf, bitfile *ld_esc,
                                      uint8_t *intensity_used)
{
    int8_t g, sfb;
    int8_t t = 0;
    int8_t error = 0;
    int8_t noise_pcm_flag = 1;

    int16_t scale_factor = ics->global_gain;
    int16_t is_position = 0;
    int16_t noise_energy = ics->global_gain - 90 - 256;

#ifdef PRINT_RVLC
    printf("\nglobal_gain: %d\n", ics->global_gain);
#endif

    for (g = 0; g < ics->num_window_groups; g++)
    {
        for (sfb = 0; sfb < ics->max_sfb; sfb++)
        {
            if (error)
            {
                ics->scale_factors[g][sfb] = 0;
            } else {
                switch (ics->sfb_cb[g][sfb])
                {
                case ZERO_HCB: /* zero book */
                    ics->scale_factors[g][sfb] = 0;
                    break;
                case INTENSITY_HCB: /* intensity books */
                case INTENSITY_HCB2:

                    *intensity_used = 1;

                    /* decode intensity position */
                    t = rvlc_huffman_sf(ld_sf, ld_esc, +1);

                    is_position += t;
                    ics->scale_factors[g][sfb] = is_position;

                    break;
                case NOISE_HCB: /* noise books */

                    /* decode noise energy */
                    if (noise_pcm_flag)
                    {
                        int16_t n = ics->dpcm_noise_nrg;
                        noise_pcm_flag = 0;
                        noise_energy += n;
                    } else {
                        t = rvlc_huffman_sf(ld_sf, ld_esc, +1);
                        noise_energy += t;
                    }

                    ics->scale_factors[g][sfb] = noise_energy;

                    break;
                default: /* spectral books */

                    /* decode scale factor */
                    t = rvlc_huffman_sf(ld_sf, ld_esc, +1);

                    scale_factor += t;
                    if (scale_factor < 0)
                        return 4;

                    ics->scale_factors[g][sfb] = scale_factor;

                    break;
                }
#ifdef PRINT_RVLC
                printf("%3d:%4d%4d\n", sfb, ics->sfb_cb[g][sfb],
                    ics->scale_factors[g][sfb]);
#endif
                if (t == 99)
                {
                    error = 1;
                }
            }
        }
    }
#ifdef PRINT_RVLC
    printf("\n\n");
#endif

    return 0;
}

#if 0 // not used right now, doesn't work correctly yet
static uint8_t rvlc_decode_sf_reverse(ic_stream *ics, bitfile *ld_sf, bitfile *ld_esc,
                                      uint8_t intensity_used)
{
    int8_t g, sfb;
    int8_t t = 0;
    int8_t error = 0;
    int8_t noise_pcm_flag = 1, is_pcm_flag = 1, sf_pcm_flag = 1;

    int16_t scale_factor = ics->rev_global_gain;
    int16_t is_position = 0;
    int16_t noise_energy = ics->rev_global_gain;